Seismic Design Calculation p1 to p9

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Ed. Addendum 4, Appendix E- Seismic Design of  Storage Tank 

NOTATIONS: 

Impulsive design response spectrum acceleration coefficient, %g Convective design response spectrum acceleration coefficient, %g Vertical earthquake acceleration coefficient, %g Nominal tank diameter, m Acceleration-based site coefficient (at 0.20 s period) Allowable longitudinal shell membrane compression stress, MPa Minimum specified yield strength of shell course, MPa Velocity-based site coefficient (at 0.1 s period) Minimum specified yield strength of bottom an nulus, Mpa Specific gravity Effective specific gravity including vertical seismic effects = G (1 – 0.40Av) Maximum design product level, m H  Importance factor coefficient set by seismic use group I  J  Anchorage ratio Coefficient to adjust the spectral acceleration from 5% to 0.5% damping K  = 1.50 unless otherwise specified M r w  Ring wall moment, Nm Q  Scaling factor from the MCE to the design level spectral acceleration Force reduction factor for the impulsive mode using allowable stress design Rwi  method Rwc  Force reduction coefficient for the convective mode using allowable stress design method Mapped, maximum considered earthquake, 5 % damped, spectral response So  acceleration parameter at a period of zero seconds(peak ground acceleration for a rigid structure), %g The design, 5% damped, spectral response acceleration parameter at short periods DS  (T = 0.20 s), %g Mapped, maximum considered earthquake, 5% damped, spectral response S  acceleration at short periods (0.20 s), %g (t) Thickness of the shell ring under consideration, mm ( ta  ) Thickness of the bottom plate under the shell extending at least the distance, L, from the inside of the shell, less corrosion allowance, mm ( tb  ) Thickness of bottom less corrosion, mm ( t  ) Thickness of bottom shell course les corrosion allowance, mm Natural period of vibration of the tank and contents, seconds T  Natural period of the convective (sloshing) mode of behavior of the liquid, T C  seconds T L Regional-dependent transition period for longer period ground moti ons, seconds (0.20Fv/S1) / (FaSS) T O  T S    FvS1/FaSS Resisting force of tank contents per unit length of shell circumference, N/m wa  Ai  Ac  Av  D  F a  F c  F t  F v  F y  G  Ge 

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wt  W  Wi  Wp  Wr  Wr  W  Xc  Xi  Xr  X 

( σ c ) 

Tank and roof weight acting at base of shell, N/m Effective convective (sloshing) portion of the liquid weight, N Effective impulsive weight of the liquid Total weight of the tank contents based on the design specific gravity of the  product, N Total weight of fixed tank roof including framing, knuckles, any permanent attachments, N Roof load acting on the tank shell, N Total weight of tank shell and appurtenances, N Height from the bottom of the tank shell to the center of action of lateral seismic force related to the convective liquid force for ring wall moment, m Height from the bottom of the tank shell to the center of action of lateral seismic force related to the impulsive liquid force for ring wall moment, m Height from the top of the tank shell to the roof and roof appurtenances center of  gravity, m Height from the bottom of the tank shell to the shell’s center of gravity, m Maximum longitudinal shell compression stress, Mpa

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Reference Tables

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